Conventionally, zoom lenses of the two group type, constituted by a first lens group having a negative refractive power and a second lens group having a positive refractive power in this order from an object side, that change magnification by moving the first lens group and the second lens group in the direction of the optical axis, are known as zoom lenses having variable magnification ratios of approximately 2.5× and wide angles. This type of zoom lens is favorably employed for miniature video cameras and the like.
For example, Japanese Unexamined Patent Publication No. 2002-277737 discloses a zoom lens of the two group type having four lenses in a first lens group (Example 1). The first lens group of this zoom lens has a negative lens (a lens having a negative refractive power), a negative lens, a negative lens, and a positive lens (a lens having a positive refractive power), provided in this order from the object side. U.S. Pat. No. 6,441,967 discloses a zoom lens having a similar lens configuration (Example 1).
U.S. Pat. No. 6,940,655 discloses a zoom lens of the two group type having four lenses in a first lens group (Example 1). The first lens group of this zoom lens has a negative lens, a positive lens, a negative lens, and a positive lens, provided in this order from the object side. U.S. Pat. No. 6,169,635 discloses a zoom lens having a similar lens configuration (Example 4).
U.S. Pat. No. 7,046,454 discloses a zoom lens of the two group type having four lenses in a first lens group and four lenses in a second lens group (Example 1). The first lens group of this zoom lens has a negative lens, a negative lens, a negative lens, and a positive lens, provided in this order from the object side. The second lens group of this zoom lens has a positive lens, a positive lens, a negative lens, and a positive lens, provided in this order from the object side. U.S. Pat. No. 8,085,474 discloses a zoom lens having a similar lens configuration (Example 1).